package train48days;

import java.util.Scanner;

public class 客似云来 {
    public static void main(String[] args) {
        Scanner sc =new Scanner(System.in);
        while (sc.hasNext()) {
            int from = sc.nextInt();
            int to = sc.nextInt();
            long[] arr =Fibonacci();
            long sum = 0;
            for (int i = from; i <=to ; i++) {
                sum +=arr[i];
            }
            System.out.println(sum);
        }
    }

    private static long[] Fibonacci() {
        long[] arr = new long[81];
        arr[0] = 1;
        arr[1] = 1;
        for (int i = 2; i <81 ; i++) {
            arr[i] =arr[i-1]+arr[i-2];
        }
        return arr;
    }

}
